Persistent high PM pollution in the Eastern Mediterranean and Middle East: insights from long-term observations and source apportionment in Cyprus

Long-term daily PM 2.5 and PM 10 chemical speciation data was collected continuously from 2015 to 2023 at an urban traffic and regional background site in Cyprus, offering a unique opportunity to quantify the influence and trends of (i) local emissions on urban PM concentration levels and sources, and (ii) regional PM emissions over the Eastern Mediterranean basin. Despite a statistically significant drop in PM 2.5 and PM 10 at both sites over the last 19 years (2005–2023), concentration levels remain high with no further significant improvements observed over the last 9 years; making PM concentration levels well above the new EU annual limits. To refine this analysis, long-term trends (2015–2023) were explored for individual PM chemical species and sources derived by PMF source apportionment. A decreasing trend in traffic-related PM 10 of 35 % was observed at the traffic site, suggesting the effectiveness of the gradual shift of the vehicle fleet towards the latest EURO-standard vehicles. On the other hand, this reduction in tailpipe traffic emissions was completely offset by an increase of uncontrolled urban emissions, such as road dust re-suspension and biomass burning from domestic heating, calling for the rapid implementation of abatement measures. Based on cluster analysis of air mass origins, the Middle East region was identified as a major hotspot of PM 10 over the Eastern Mediterranean; with both high concentration levels of dust from the Arabian desert and substantial anthropogenic pollution with continuously increasing trends in biomass burning and sulfate-rich emissions from fossil fuel combustion over the past decade.